A double flywheel of the above kind is disclosed in the specification of French published patent application No. FR 2 629 166A. In that specification, the two series of resilient means are arranged to cooperate with a damper plate which is part of one of the two inertia masses, and with guide rings which are part of the other inertia mass. The damper plate is provided with windows in which the resilient means of the second series are engaged, while the first series is arranged at the outer periphery of the damper plate and is arranged to intercept arms formed on the damper plate.
That arrangement does enable the axial size of the assembly to be reduced, but at the cost of greater radial size. In this connection, the damper plate has integral bar-like elements which define the said windows, and these bar-like elements have to have at least a certain thickness for reasons of mechanical strength and for manufacturing reasons, particularly in connection with pressing operations. In addition, frictional effects occur between these bar-like elements and the resilient means of the two said series.